Ultra high frequency electric discharge device



g- 10, 1948- A. M. GUREWITSCH 2,446,825

ULTRA HIGH FREQUENCY ELECTRIC DISCHARGE DEVICE Filed Dec. 51, 1.942 I Inventor: Anatole M. Gurewitsch,

y His Attorne;

Patented Aug. 10, 1948 "2446325 ULTRA TH'iGH" FREQUEl$IY et'sorm'c DISCHARGE DEVICE Anatole Gurewitsch, Schene'ctady. "N. as-

'si'g'nor to General Electric" Company, a

' ration of- New-York sp lieauonneeember '1 Claim. '1

"My invention relates 'to 'ii ltra high frequency electric dischargedevices and more particularly to iil-tra high frequency-discharge devices of the magnetron type. a

In the prior art electric discharge devices of the space chargehas been fiected. In accordance with the teachings'of my invention described hereinafter, I provide new and improved ultra high frequency magnetrons' and methods of operating such devices wherein more efiective utilization of the energy" ofthespace charge is obtained.

It is an objectofm'y invention'to'provide new and improved ultra. high' frequency electric discharge devices.

-It'is another object of myinvention to provide -n'ew and improved ultrahigh frequency electric discharge devices or the magnetrontype whereinelectron permeable or pe'rvious 'anode structures are provided so'that electrons having relatively large radial paths are efiectively employed to obtain'the desired transfer of energy b'etween the-field of the anodestructuresandthe electrons constituting the rotatingspa'ce charge.

It is a" further object of my invention to pro- "vide a new and improved ultrahigh frequency magnetron wherein an electron-permeable anode structure establishes an electromagnetic field pattern, and which permits the passageof the electron space charge there'through and wherein the electrons of the spacecharge'undergocyclic "variations in velocity for effecting interchange of energy between the field'ofthe anode structureandthe space charge.

"It is a still further object'otmy'inventionto provide new and improved'methods ofoperat- 'ing ultra high frequency -'magnetrons.

Briefly stated, in one of the illustrated embodiments of my invention I'providean ultra hig h modeof electrical oscillation, -"establishing therecorpo- I 31, mizjsenai'iwof'iionss by a* predet'rininted-electromagnetic field patte' fn *A are so "correlated the f''elec't'rons paths of aippreciable radii-"extending hollow anodereg-ion ting witlithee magnetic-fields;or'ifield at'tins; to"effect ransfer 'of-hig'h' frequency energy to the anode field, or derive "energy therefrom. fsuch -f travel,

within the electron-permeable anod electrons iiri'dergo substat velocity; siifiplying efiergy g 'fromjtlie field depending 'po'n' the} purpose for which the oischaige dev'i'ce' as a 'v'i hole is "'r'nploye'd.

electrons elative to the electfonragntic field patter c arigesto a point whe're hese' 'e'l -tron -"wou1a tend toa'b'sorb energy 'fromthe field ode vereneig'y' to'the"fieldfdependingupon h'e' device 'iseir'iployed'for' thep'rodiictioh "or'fiti-li'zation -of the traliiglr freduencyeriig'y. -In accordance with another ixibodi-nien of my 'ihventio'nfl provide an -iiltra high nequ ri'y magnetron wherein the anode structure coniprise's a -plurality of spaced w afer-like'- metallic dis ks "which are placed inal ineinentf and 'ea'ch ti which includes an enlarged 'central"ripening ar'1'd= a plura-lity 6f circumferentially spaced,

space-resonant regions or cavities i'n conirhu'r'ii- ':ati6n 't'ritli-the associated central ope g. fay i irtue of -t-he spaces" tween the Various 'dislgs, "there" is rot/Med ate angement"for-"perifiittiiig tial iotatib'nal motion of the' electr'bns con- 'tng 1 the *space'enarge "between the "various so thatthekin'etic energy of theioscilla'ting ybe"n1fore"efficientlyutiliied.

nee with 2. Still further modifica- "t'ion' ofmveiitrongr provide'an ultra high ire- "'quency magnetron "wherein the anode structure comprises *a met'allic annular "member provided with "a pliiralit y of inwar'dly extending proti1- berances formed hy ai plurality of'longitiidinarand circumferential fiutingsthe protuberances de'fin- --irig aplurality of' space resonant regions or cavi- "t'ie's 'which'in' codperationwith the orbital motions oft-he "electrons constitute efficient means for effectin'gtran'sfer' of' energy therebetween.

For a "better understanding "of my invention,

fication of my invention wherein the anode struc-' ture comprises a plurality of spaced metallic disks each of which includes a plurality of space resonant regions or cavities, and Fig. 4 is a plan view of one of the disk members shown in Fig. 3. Fig. 5 illustrates a still further modification of my invention wherein an annular anode member furnishes a plurality of space resonant regions formed by longitudinal and circumferential fiutings. I Y

Prior to adescription of the various embodiments of my invention, it is believed that it may be helpful to review generally fundamental physical aspects relating to the operation of electric dischargedevices of the magnetron type wherein there is provided an anode, a cathode, an electric field between the anode and the cathode, and a magnetic field at right angles to the electric field.

Due to theinteraction of the electric and magnetic fields in devicesof this nature, the electrons constituting the space charge between the anode and the cathode undergo: both rotational and translational motion, that is rotational motion. about the centrally located cathode and translational ,motion along the principal axis of the cathode. Neglecting the initial electron velocities at the cathode surface, and considering only planar movement, the electrons assume rotational and radial motions which produce a magnetic force substantially equaland opposite to the electric force acting thereon in the radial direction. Stated in other words and viewing the phenomenon from anacceleration standpoint,

the net accelerating force upon each electron is equal to the difierence between the. applied electric force and the opposing magnetic force due to the radial and tangential motions of the electron. V

'The total kinetic or rotational energy of the electrons of the space charge maybe analyzed as comprising two components, one is the energy due to motion along the radii, and the other is have been of such character that a substantial v, portion of the rotationalenergyof the electrons is not utilized because theelectrons, just at the points or places in their orbital motions at which the electrons develop appreciable rotational energy, strike the opposing anode surfaces, thereby dissipating the energy at those surfaces in the form of heat rather'than supplying the energy to the associated space resonant region.

'In accordance with one feature of my invention, the electrons are intentionally afforded relativelylarge spiral or orbital paths extending into the electromagnetic field established by an electron-permeable or pervious anode structure wherein an appreciable part of theelectron ro- 4 tational energy is utilized, and wherein the anode structure is of such size and configuration that a large percentage of the energy-delivering electrons do not come in contact with the anode structure until the electrons have delivered a substantial portion of their energy to the field.

Referring-now. to Fig, 1 of. the accompanying drawing, I-have there illustrated my invention as applied to an ultra high frequency magnetron including a plurality of enclosed electrodes which are positioned within an enclosing envelope such asa glass or vitreous envelope I. The electrodes comprise a cathode, such as a cylindrical thermionic cathodeZ, which may include a cylindrical or tubular metallic braid 3 coated with a suitable electron-emissive material and which is connected to an externally accessible terminal 4 through lead-in conductor 5 and a metallic strap 6., The cathode 2 also comprises an inner conductor (not shown) concentric with the cylindrical braid 3 terminated in a lead-in conductor I which extends to an externally accessible terminal 8. Lead-in conductors 5 and 1, are, of course, sealed to the bottom of container I.

I provide an anode structure 9 which is electron-permeable or pervious to permit the travel of electrons constituting the space charge within the electromagnetic field defined thereby. The anode structure 4 may comprise a hollow anode member 9 which is shown broken away in Fig. 1, and may have a U-shaped cross section, the top part I 0 and the bottom part I I constituting transverse members for defining the electromagnetic field in the longitudinal direction. The anode member 9 is constructed of conductive material, preferably of a metal such as copper or brass, and may be provided with a plurality of longitudinal members l2 placed within the vicinity of the enlarged circular openings l3 and II in the top and bottom parts l0 and H, respectively.

netic field pattern established within the anode member 9. Additional mechanical support for the hollow anode structure may be afforded by a plurality of radially extending vanes or rods l5 which extend from the longitudinal wall of the anode member 9 to the longitudinal supporting rods l2. Although my invention is not limited thereto, the rods I5 may also be employed for the purpose of assisting in the definition of the electromagnetic field patterns established within the anode member 9.

As a means for limiting the longitudinal movement of some of the electrons constituting the space charge of the device which tend to travel beyond the effective anode region, transverse disks l6 and I! may be supported by the cathode structure Z-and may be placed appreciable distances from the top and bottom parts l0 and l Lrespectively, of the anode member 9.

Electrical connections to the anode member 9 may be obtained by means of lead-in conductors I8 and 19 which are sealed insuitable tubulations at thetop of the envelope l affording externally a-ccessible'members 20 and 2|. If desired, only one such anode connection need be employed from an electrical standpoint, and in the embodiment of my invention jllustratedthe two lead-in conductors l8 and I9 also serve as mechanical means for supporting the anode memareas-2e her; a in desired. space relation. with the. cathode structure 2. The entire device may be evacuated through a tabulation 2-2 which is sealed after the evacuation isv accomplished;

A magnetic field is provided by employing. an

electromagnetic coil: 23 surrounding: that portion or the envelope I immediately opposite the anode part9. The'electromag-netic field so produced is substantially parallel to the longitudinal: axis trical conductors 25 ancle 26 which are sealed ina suitable glass press on the side of envelope t. The press and conductors 25 and 26 may extend through an opening in coil- 23.

Upon the application of a unidirectional volt-- age between the anode part 9 and the cathode structure 2, and upon properenergization of'the coi-l 23gthe electrons constituting the space charge will= be given rotational motion. Bythe propercorrelation of the magnetic field intensity, the electric-field intensity and the anode-field, the rotational motion of the electrons is suflicient to cause the electrons to traverse the interior region defined by the anode member 9.

The anode member 9- by virtue of its dimensions and configuration establishes a predeterminedelectromagnetic field pattern in accordance With itselectromagnetic mode or modes of oscillation. These patterns-of the electromagnetic field are, of course, determined by the radius of the anode part- 9 and particularly the radius of the outside diameter thereof and theradii of the apertures'or openings [3 and I4. From an elementaryanalysis point of view for the sakeo-f obtaining a visual impression of the nature of the electromagnetic field patterns so established, it may be postulated that the circumferential distribution of the-field at any one time comprises aplurality of segmental fielclsections such that 1 adjacent segmental field sections are of opposite polarity. Of, course,.these polarities are not fixed but are continuously undergoing a time variation, such as a sinusoidal time variation. Although not limited to a structure wherein means are provided within the anode part 9, the longitudinal rods l2 and the radial rods 45 may be employed. for the purpose of: assisting in the definition of the-electromagnetic field pattern.

By virtue of the electron-permeability of the anodet member 9, the electrons constituting the space charge are given spiral paths having relatively large radii extending into the enclosed anode region of member 9 and there undergo cyclical variationsin velocity to absorb energy from the magnetic field thereof, or to deliver energy thereto, depending upon. the purpose for which the-device-as a whole islemployed.

For. example, when the device is employed for generating ultra high frequency electromagnetic Waves, the electrons which pass into the anode region deliver energy to the electromagnetic field, and by virtue of the structure which permits substantial rotary motion with a minimum of structure for impeding such motion, a large portion of the rotational energy of the electrons is effectively utilized.

Referring now to the phenomenon by virtue of which energy may be extracted from the electrons constituting the space charge and delivered to the 6 electromagnetic field, it. will oi course be cia'ted: that electronsleaveithe cathode in all time phase. relationships; that is tov say, not: all; of the electrons which are emitted fromthe cathode are efieetive in transferring energy to the electromagnetic. field of the anode part 9; More specifiically, of course, onlyrthose electrons which leave the cathode andenter the electromagnetic field in a predetermined time relation: with respect to. theanode-electromagnetic field are effective; in delivering energy to the: field; it may be said that the. electrons whichv l'eavezthe cathode and which enter the anode region at a time when: the electric field, or the electromagnetic field for that particular region exerts an acceler ating effect, absorb energy from the electromagneticfield; These electrons do: not: remain within. the anode region for periods of time comparableto the periods of dwell for the energy-delivering electrons because the increased potential oi the anode field during such time adds: to the ap plied electric field, causing these electrons either to strike an anode part on the first outward trip. or to return rapidly to the cathode withinone cycle. On the other hand, the electrons which leave the cathode and enter the electromagnetic field at a time when the potential or the electromagnetic field exerts a decelerating effect thereondeliver energy to=the-field; that is, these electrons are slowed clownin their motion, kinetic energy thereof beingdelivered tothe electromagnetic field. Consequently these electrons remain within the anode region for substantialy longer peri ods-of't-ime; and undergo'successiveor cyclic variations in velocity todeliver energy to the elec tromagneticfield. In other words, the aggregate effect of the energy-delivering electrons is greater than the-effect of the electrons which. ab-- sorbenergy from the electromagnetic field.

In Fig; 2' there is diagrammatically illustrated a simplified plan view of the-path of an energydelivering electron which is emitted from thecathode cylinder- 3' and which enters the hollow anode region, traversing or passing through theelectromagnetic field thereof.

the anode structure hasbeenshown as comprising only six" segmental parts: designating graphically three complete cyclic distributions of pote'nti'alii'nwhich adjacent segments maybe-considered; for the purpose of elementary analysis; as comprising field sections of instantaneously differentpolarities. The dotted curve A indicatesthe probable mean path of an energy-delivering electron. The, heavycurve B represents-a prob"- ablepath of an energy-delivering electron having rotational motion within the anode part 9;.and at theisame time undergoing radial changes inposition incident to the interaction with the anode field.

In accordance with a still. further feature; of'

my invention, the dimensions of the anode part Q'maybe correlated relative to the electron paths" so that the energy-delivering; electrons are outside the effective range of the anode region when sufiicient energy, or a substantial portion of their energy, has been converted or extracted by the electromagnetic field. As the electrons deliver energy to the field, the phase position of the electrons relative to the instantaneous values of the high frequency field pattern advances in phase relative to the anode field, and this advance will continue to a point where the electrons would tend to absorb energy from the field unless the electrons are effectively removed from the anode Generally speaking,v

For the purpose of simplification of this aspect of my invention,

region. By the proper correlation of the dimen-' sions of the anode part 9, the electrons which have spent the greater portion of their energy may be caused to pass outside the efiective range of anode part 9. For example, the electrons may be made to impinge on the top, the bottom or side wall of the anode part 9.

Fig. 3 diagrammatically illustrates a modificationof my invention wherein anode structure is provided which also permits utilization, in a large measure, of the rotational energy of the electrons in supplying energy to the electromagnetic field of a space resonant region or cavity. In this modification of my invention, I provide a plurality of wafer-like metallic disks 21--3l in alinement and which are maintained indesired axial displacement by means of a plurality of annular spacers 32. The complete anode structure may be assembled as a unit and ,held in position by means of a fixture 33 supported from the inside of an envelope 34 comprising the enclosure for an electric discharge device of the general type shown in Fig. 1.

Each of the disks 21-31 is provided with an enlarged central opening 35 in alinement with similar openings and through which the cathode cylinder 3 extends. A more detailed view of the disk construction may be obtained by referring to the plan view shown in Fig. 4 wherein the disk 21 is shown as comprising the enlarged central opening 35 in communication with a plurality of circumferentially spaced space-resonant regions or cavities which may take the form of a plurality of circular openings 36 in communication with the large central opening 35 by means of radial slots 31. Each of the openings 36 and its associated slot are dimensioned to be resonant to a particular frequency. These cavities may be viewed as afiording the principal component of inductance by virtue of openings 36, and the capacitance component may be considered as being furnished primarily by the opposing surfaces of slots 31. Energy may be extracted from or supplied to the various space resonant regions by an electrode means which may take the form of a loop 38 extending into the opening and which comprises an extension of a concentric transmission line including a conductor 39 and an outer tubular conductor 40.

The operation of the embodiment of my invention illustrated in Figs. 3 and 4 is essentially the same as that explained above in connection with Fig. 1. In this modification of my invention, the anode structure is also designed to afford a small area or surface against which the electrons may impinge, thereby causing the electron space charge to lose only a relatively small amount of energy in the form of heat by impingement on the anode structure. Stated in other words, the spaces between disks 21-31, inclusive afford appreciable regions within which the electrons describe paths of relatively large radii, thereby delivering a substantial portion of the rotational energy to the electromagnetic fields of the various space resonant regions.

A still further embodiment of my invention is illustrated in Fig. 5 wherein anode structure, shown broken away, comprises an annular metallic cylinder 4| surrounding the cathode cylinder 3. The anode cylinder 4| is provided with aplurality of inwardly extending protuberances 42 de-- fining therebetween a plurality of space resonant regions 43. The space resonant regions may be formed by a plurality of interconnected circumferential and longitudinal flutes or channels.

The modification of my invention shown in Fig. 5 also provides paths for the efiective utilization of the energy incident to the electrons which describe paths of relatively large radii inasmuch as the electrons may traverse the channels between longitudinally displaced protuberances, delivering energy to the electromagnetic fields of the various space resonant regions.

While I have shown and described my invention as applied to particular devices. it will be obvious to those skilled in the art that changes and modifications may be made without departing from my invention, and I, therefore, aim in the appended claim to cover all such changes and modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

An electric discharge device of the magnetron type comprising an elongated cathode, an anode comprising a multi-cavity resonator surrounding said cathode and including a generally cylindrical conductive member, and a plurality of conductive structures electrically connected to and supported from said cylindrical member and extending radially inwardly in circumferentially spaced relation toward said cathode and terminating short of the cathode to define an interelectrode space, said conductive structures defining substantial open spaces in a circumferential direction through which electrons may pass without being collected by said anode when moving within said anode under the action of a magnetic field substantially parallel to said cathode and a substantially radial electric field.

ANATOLE M. GUREWITS'CH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,387,985 Hull Aug. 16, 1921 1,684,947 Daumann Sept. 18, 1928 1,978,021 Hollmann Oct. 23, 1934 2,005,793 Lindenblad June 25, 1935 2,043,733 Brasch et al. June 9, 1936 2,207,846 Wolfi July 16, 1940 2,247,077 Blewett et al June 24, 1941 2,250,698 Berline July 29, 1941 2,270,777 Von Baeyer Jan. 20, 1942 2,288,812 Linder July 7, 1942 2,417,789 Spencer Mar. 18, 1947 

